The Fleet – London’s Underground River

13 October 2014

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If you listen carefully just above this unassuming grate you can hear the ripple and splash of flowing water. This is the sound of the River Fleet, London’s largest subterranean river. Forced underground by the city’s burgeoning populace the river still flows from its source to its mouth where it joins London’s main waterway, the Thames. Yet what lies beneath?

Below the ground there is a remarkable network of tunnels and chambers, put in to place by Victorian engineers, the final step in a process which took centuries. For over a thousand years there had been a shipping dock at the mouth of the river – its name comes from the Anglo-Saxon fleot which means a tidal inlet. Yet it was not destined to persevere as a river in its own right.

The Fleet remains tidal and these incredible pictures, taken by Flickr photographer sub-urban, show the river at its lowest level. Visitors must remain vigilant of the time as it fills to the roof in thirty minutes. Even as the time draws towards low tide the water is way above the height of a man. A short time at the upper levels and it empties out although it would be easy for the unwary traveller to be trapped and drowned on its return.

Everything is in place, thanks to the ingenuity of the Victorian engineers, to ensure that the Fleet is confined to these tunnels. Yet it was not always like that. If we travel back a few centuries we find a different story altogether – one which is not without its own pathos if such an emotion can be felt for a river.

Then, the waters of the Fleet were renowned for being clear and sparkling. As the medieval city began to grow, mills, tanneries and meat markets sprang up along its banks. Water was vital to keep these industries functioning and growing and gradually the river was polluted with blood, sewage and other waste – it effectively became a waste tip, a handy repository to discard anything unwanted including the carcasses of dead livestock.

As a result, over the years the river became shallower and the water much slower than in previous generations, only exacerbating the burgeoning problem of the health hazard it now presented. It would silt up in the summer and although the spas and wells upstream remained open and functioning the Fleet in the city of London became an open sewer with a mix of slums and prisons on its banks. Something had to be done.

The Great Fire of London in 1666 provided that opportunity. The architect Sir Christopher Wren was afforded the chance of transforming the lower Fleet.

By 1680 this part of the river had been turned in to the New Canal. It was hailed as the Venice of England but its days were numbered from the very beginning.

It was poorly used as a canal and, despite its new clothes, it still stank to high heaven. The satirical cartoon, right, shows the new canal and the undesirables it attracted. Within a generation it was no longer fit for purpose as a canal.

The river was channelled underground in the 1730s from Holborn to Fleet Street, which still bears its name. Decades later it was filled in and arched over from Fleet Street down to the river Thames and is covered by what is now New Bridge Street.

The mouth of the river on the Thames was still used by ships in 1750, as the painting above by Samuel Scott testifies, but that was all. Towards its source it fared no better as the Industrial Revolution spread and the population of London increased. Urban growth and the creation of what came to be known as suburbia meant that it was further submerged in the early years of the nineteenth century.

Yet the final blow was to come in the 1860s. It was at this point that the sunken river was incorporated in to the new network of sewers – an astonishing piece of industrial scale engineering designed by the visionary civil engineer Joseph Bazalgette. A little later its upper reaches in Hamstead and Kentish Town disappeared forever as well.

Massive iron conduits for the river were placed along its route, including the one under St.Pancras station, above. They can still be rediscovered today by the brave and hardy souls willing to brave the depths.

The story of the Fleet is one of almost inevitable but inexorable decline. Over the period of just a few hundred years it went from a river to a brook. From there, despite a brief renaissance as a canal it became a ditch and ultimately was consigned to the depths as a drain. Human intervention has consigned the river to its labyrinthine underground tomb. Yet take a visit to the ponds of Hampstead and you can still see it, at its source, perhaps something akin to how it looked before we arrived.